This relates to semiconductor fabrication processes.
A three dimensional isolation structure is an isolated semiconductor structure with trenches in two perpendicular directions. This structure results in the formation of a regular array of trench isolated pillars. The shape of the pillars is a function of the spacing between the trenches formed in each of the two perpendicular directions.
In most trench filling operations using a conformal deposit, a seam is formed in the deposit. The seam or void is centrally located in the deposit. This void will then be exposed to subsequent wet etches and cleanings, which can result in damage. Moreover, the conformal film is generally annealed. A wet anneal may be used to close seams and a dry anneal at a higher temperature may be used to decrease the wet etch rate of the film. Thus, the thermal budget may be increased due to the presence of the seams.